Internal combustion engine with a main combustion chamber and an auxiliary combustion chamber

Abstract

A spark ignited internal combustion engine includes a main combustion chamber, an auxiliary combustion chamber connected to the main combustion chamber, and fuel delivery means for supplying separate partial quantities of fuel to the main combustion chamber and auxiliary combustion chamber. Since the auxiliary combustion chamber is maintained at an elevated operating temperature and the partial quantity of fuel delivered to the auxiliary combustion chamber is an easily dissociable fuel, thermal dissociation of the easily dissociable fuel may occur prior to ignition.

We claim: 
     
       1. In a spark ignited internal combustion engine including a main combustion chamber, an auxiliary combustion chamber connected to the main combustion chamber, and fuel delivery means for supplying separate partial quantities of fuel to the main combustion chamber and auxiliary combustion chamber; the improvement wherein: the partial quantity of fuel delivered to the auxiliary combustion chamber is an easily dissociable fuel capable of substantial thermal dissociation at an elevated operating temperature; said improvement comprising means for constantly maintaining the auxiliary combustion chamber at the elevated operating temperature, and means, including the auxiliary combustion chamber, for dissociating the easily dissociable fuel, the main combustion chamber and the auxiliary combustion chamber being in continuous communication with each other so that prior to ignition of a fuel-air mixture in the main combustion chamber a predetermined amount of dissociated fuel mixes with the fuel-air mixture to contribute to exhaust gases low in noxious substances.   
     
     
       2. The internal combustion engine of claim 1, wherein the easily dissociable fuel is methanol. 
     
     
       3. The internal combustion engine of claim 1, wherein a predetermined quantity of water is delivered to the auxiliary combustion chamber with the easily dissociable fuel. 
     
     
       4. The internal combustion engine of claim 1, wherein the internal combustion engine further comprises a cylinder head having a cavity delimited by surrounding walls of the cylinder head; and wherein the auxiliary combustion chamber includes a thin-walled shell positioned in the cavity and spacedly arranged from the surrounding walls of the cylinder head of the internal combustion engine. 
     
     
       5. The internal combustion engine of claim 4, wherein the thin-walled shell is manufactured from a thermally conductive material, whereby the auxiliary combustion chamber is heatable. 
     
     
       6. The internal combustion engine of claim 5, wherein the auxiliary combustion chamber is heated with hot exhaust gases emitted from the internal combustion engine. 
     
     
       7. The internal combustion engine of claim 1, wherein the fuel delivery means comprises an injection nozzle communicating with the auxiliary combustion chamber for supplying the easily dissociable fuel thereto. 
     
     
       8. The internal combustion engine of claim 1, wherein the fuel delivery means comprises an auxiliary intake valve communicating with the auxiliary combustion chamber for delivering a fuel-air mixture containing the easily dissociable fuel to the auxiliary combustion chamber. 
     
     
       9. The internal combustion engine of claim 1, further comprising a spark plug provided in the main combustion chamber for igniting a cylinder charge comprising the separate partial quantities of fuel. 
     
     
       10. The internal combustion engine of claim 9, further comprising an auxiliary spark plug provided in the auxiliary combustion chamber for delivering an ignition spark in synchronization with the ignition of the spark plug of the main combustion chamber.